I. Introduction
The following description includes information that may be useful in understanding the present invention. It is not an admission that any such information is prior art, or relevant, to the presently claimed inventions, or that any publication specifically or implicitly referenced is prior art or even particularly relevant to the presently claimed invention.
II. Background
The present invention relates to methods of decreasing or attenuating aberrant neovascularization, angiogenesis, aberrant fibrogenesis, fibrosis and scarring, and inflammation and immune responses. These processes, separately or together are involved in many diseases and conditions. These diseases or conditions may be systemic or may be relatively localized, for example to the skin or to the eye.
A. Ocular Diseases and Conditions
Pathologic or aberrant angiogenesis/neovascularization, aberrant remodeling, fibrosis and scarring and inflammation occur in association with retinal and ocular ischemic diseases such as age-related macular degeneration (AMD), diabetic retinopathy (DR) and in retinopathy of prematurity (ROP) and other developmental disorders [Eichler et al. (2006), Curr Pharm Des, vol 12: 2645-60] as well as being a result of infections and mechanical injury to the eye [Ciulla et al. (2001), Curr Opin Ophthalmol, vol 12: 442-9 and Dart et al (2003), Eye, vol 17: 886-92].
Pathologic ocular angiogenesis is a leading cause of blindness in a variety of clinical conditions. Choroidal neovascularization (CNV) occurs in a number of ocular diseases, the most prevalent of which is the exudative or “wet” form of AMD. As a result of an increasingly aged population, AMD is a modern day epidemic and the leading cause of blindness in the western world in patients over age 60. Despite the epidemic of vision loss caused by AMD, only a few therapies, mostly anti-VEGF based, can slow the progression of AMD and even fewer can reverse vision loss [Bylsma and Guymer (2005), Clin Exp Optom., vol 88: 322-34, Gryziewicz (2005), Adv Drug Deliv Rev, vol 57: 2092-8 and Liu and Regillo (2004), Curr Opin Ophthalmol, vol 15: 221-6.]. Therefore, discovering new treatments for pathologic neovascularization is extremely important.
AMD is used here for illustrative purposes in describing ocular conditions relating to aberrant angiogenesis/neovascularization, aberrant remodeling, fibrosis and scarring, and inflammation, which conditions are found in other ocular diseases and disorders as disclosed and claimed herein. AMD involves age-related pathologic changes [Tezel, Bora and Kaplan (2004), Trends Mol Med, vol 10: 417-20 and Zarbin (2004), Arch Ophthalmol, 122: 598-614]. Multiple hypotheses exist but the exact etiology and pathogenesis of AMD are still not well understood. Aging is associated with cumulative oxidative injury, thickening of Bruch's membrane and drusen formation. Oxidative stress results in injury to retinal pigment epithelial (RPE) cells and, in some cases, the choriocapillaris [Zarbin (2004), Arch Ophthalmol, vol 122: 598-614 and Gorin et al. (1999), Mol Vis., vol 5: 29]. Injury to RPE likely elicits a chronic inflammatory response within Bruchs membrane and the choroid [Johnson et al. (2000), Exp Eye Res., vol 70: 441-9]. This injury and inflammation fosters and potentiates retinal damage by stimulating CNV and atrophy [Zarbin (2004), Arch Ophthalmol, vol 122: 598-614 and Witmer et al. (2003), Prog Retin Eye Res, vol 22:1-29]. CNV results in defective and leaky blood vessels (BV) that are likely to be recognized as a wound [Kent and Sheridan (2003), Mol Vis, vol 9: 747-55]. Wound healing arises from the choroid and invades the subretinal space through Bruchs membrane and the RPE. Wound healing responses are characterized by a typical early inflammation response, a prominent angiogenic response and tissue formation followed by end-stage maturation of all involved elements. Wound remodeling may irreversibly compromise photoreceptors and RPEs thereby, justifying the need to treat CNV with more than anti-angiogenic therapies [La Cour, Kiilgaard and Nissen (2002), Drugs Aging, vol 19: 101-33.12].
Alterations in the normal retinal and sub-retinal architecture as a result of CNV related fibrosis, edema and inflammation individually or cumulatively, leads to AMD related visual loss [Tezel and Kaplan (2004), Trends Mol Med, vol 10: 417-20 and Ambati et al. (2003), Sury Ophthalmol, vol 48: 257-93]. The multiple cellular and cytokine interactions which are associated with exudative AMD greatly complicate the search for effective treatments. While CNV and edema are manageable in part by anti-VEGF therapeutics, potential treatments to mitigate scar formation and inflammation have not been adequately addressed [Bylsma and Guymer (2005), Clin Exp Optom, vol 88: 322-34 and Pauleikhoff (2005), Retina, vol 25: 1065-84]. As long as the neovascular complex remains intact, as appears to be the case in patients treated with anti-VEGF agents, the potential for subretinal fibrosis and future vision loss persists.
In some patients with AMD or conditions such as polypoidal choroidal vasculopathy (PCV), the retinal pigmented epithelium (RPE) may detach. This detachment is often referred to as pigment epithelial detachment (PED), and it may occur for example, in disorders such as AMD and PCV that disrupt the normal junction between the basement membrane of the RPE and the inner collagenous layer of Bruch's membrane. When the detachment affects the macula, vision is affected. Polypoidal choroidal vasculopathy (PCV) is characterized by abnormal development of blood vessels in the deeper layers of the eye; whether PCV is a sub-type of AMD or a separate disorder remains unclear.
Anti-VEGF-A therapies represent a recent, significant advance in the treatment of exudative AMD. However, the phase III VISION Trial with PEGAPTANIB, a high affinity aptamer that selectively inhibits the 165 isoform of VEGF-A, demonstrated that the average patient continues to lose vision and only a small percent gained vision [Gragoudas et al. (2004), N Engl J Med, vol 351: 2805-16] Inhibition of all isoforms of VEGF-A (pan-VEGF inhibition) with the antibody fragment ranibizumab (LUCENTIS®, Genentech) yielded much more impressive results [Brown et al., N Eng Med, 2006 355:1432-44, Rosenfeld et al. N Eng J Med 2006355:1419-31]. The 2-year MARINA trial and the 1 year ANCHOR trial demonstrated that approximately 40% of patients achieve some visual gain. Although these results represent a major advance in our ability to treat exudative AMD, they also demonstrate that 60% of patients do not have visual improvement. Furthermore, these patients had to meet strictly defined inclusion and exclusion criteria. The results in a larger patient population may be less robust. The market leaders in treatment of wet AMD are LUCENTIS® (ranibizumab) and off-label use of AVASTIN® (bevacizumab, a humanized monoclonal antibody against VEGF-A).
There is still a well-defined need to develop further therapeutic agents that target other steps in the development of CNV and the processes that ultimately lead to photoreceptor destruction. First, the growth of choroidal BVs involves an orchestrated interaction among many mediators, not just VEGF, offering an opportunity to modulate or inhibit the entire process [Gragoudas et al. (2004), N Engl J Med, vol 351: 2805-16]. Second, exudative AMD is comprised of vascular and extravascular components. The vascular component involves vascular endothelial cells (EC), EC precursors and pericytes. The extravascular component, which volumetrically appears to be the largest component, is composed of inflammatory, glial and retinal pigment epithelium (RPE) cells and fibroblasts. Tissue damage can result from either component. These other aspects of the pathologic process are not addressed by current anti-VEGF treatments. Targeting additional elements of the angiogenic cascade associated with AMD could provide a more effective and synergistic approach to therapy [Spaide R F (2006), Am J Ophthalmol, vol 141: 149-156].
1. Inflammation in Ocular Disease
There is increasing evidence that inflammation, specifically macrophages and the complement system [Klein et al. (2005), Science, vol 308: 385-9 and Hageman et al. (2005), Proc Natl Acad Sci USA, vol 102: 7227-32] play an important role in the pathogenesis of AMD, both the dry or atrophic form which accounts for 85-90% of AMD cases, and the wet form of AMD characterized by the growth of abnormal blood vessels. Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate from deposits or debris from deteriorating tissue primarily in the area of the macula. Gradual central vision loss may occur. There is no effective treatment for the atrophic (dry) form of AMD. Atrophic AMD is triggered by abnormalities in the retinal pigment epithelium (RPE) that lies beneath the photoreceptor cells and normally provides critical metabolic support to these light-sensing cells. Secondary to RPE dysfunction, macular rods and cones degenerate leading to the irreversible loss of vision. Oxidative stress, ischemia, formation of drusen, accumulation of lipofuscin, local inflammation and reactive gliosis represent the pathologic processes implicated in pathogenesis of atrophic AMD. Of these processes, inflammation is emerging as a key contributor to tissue damage. Macrophage infiltration into the macula of patients with dry AMD has been demonstrated to be an important component of the damaging inflammatory response.
In exudative AMD, histopathology of surgically excised choroidal neovascular membranes demonstrates that macrophages are almost universally present [Grossniklaus, et al. (1994), Ophthalmology, vol 101: 1099-111 and Grossniklaus et al. (2002), Mol Vis, vol 8: 119-26]. There is mounting evidence that macrophages may play an active role in mediating CNV formation and propagation [Grossniklaus et al. (2003), Mol Vis, vol 8: 119-26; Espinosa-Heidmann, et al. (2003), Invest Ophthalmol Vis Sci, vol 44: 3586-92; Oh et al. (1999), Invest Ophthalmol Vis Sci, vol 40: 1891-8; Cousins et al. (2004), Arch Ophthalmol, vol 122: 1013-8; Forrester (2003), Nat Med, vol 9: 1350-1 and Tsutsumi et al. (2003), J Leukoc Biol, vol 74: 25-32] by multiple effects which include secretion of enzymes that can damage cells and degrade Bruchs membrane as well as release pro-angiogenic cytokines [Otani et al. (1999), Ophthalmol Vis Sci, vol 40: 1912-20 and Amin, Puklin and Frank (1994), Invest Ophthalmol Vis Sci, vol 35: 3178-88] At the site of injury, macrophages exhibit micro-morphological signs of activation, such as degranulation [Oh et al. (1999), Invest Ophthalmol Vis Sci, vol 40: 1891-8 and Trautmann et al. (2000), J Pathol, vol 190: 100-6]. Thus it is believed that a molecule which limited macrophage infiltration into to the choroidal neovascular complex may help limit CNV formation.
2. Choroidal Neovascularization and Blood Vessel Maturation in Ocular Disease
Angiogenesis is an essential component of normal wound healing as it delivers oxygen and nutrients to inflammatory cells and assists in debris removal [Lingen (2001), Arch Pathol Lab Med, vol 125: 67-71]. Progressive angiogenesis is composed of two distinct processes: Stage I: Migration of vascular ECs, in response to nearby stimuli, to the tips of the capillaries where they proliferate and form luminal structures; and Stage II: Pruning of the vessel network and optimization of the vasculature [Guo et al. (2003), Am J Pathol, vol 162: 1083-93].
Stage I: Neovascularization. Angiogenesis most often aids wound healing. However, new vessels when uncontrolled, are commonly defective and promote leakage, hemorrhaging and inflammation. Diminishing dysfunctional and leaky BVs, by targeting pro-angiogenic GFs, has demonstrated some ability to slow the progression of AMD [Pauleikhoff (2005), Retina, vol 25: 1065-84.14 and van Wijngaarden, Coster and Williams (2005), JAMA, vol 293: 1509-13].
Stage II: Blood vessel maturation and drug desensitization. Pan-VEGF inhibition appears to exert its beneficial effect mostly via an anti-permeability action resulting in resolution of intra- and sub-retinal edema, as the actual CNV lesion does not markedly involute [Presentation. at Angiogenesis 2006 Meeting. 2006. Bascom Palmer Eye Institute Miami, Fla.]. The lack of marked CNV involution may in part be a result of maturation of the newly formed vessels due to pericyte coverage. Pericytes play a critical role in the development and maintenance of vascular tissue. The presence of pericytes seems to confer a resistance to anti-VEGF agents and compromise their ability to inhibit angiogenesis [Bergers and Song (2005), Neuro-oncol, vol 7: 452-64; Yamagishi and Imaizumi (2005), Int J Tissue React, vol 27: 125-35; Armulik, Abramsson and Betsholtz (2005), Circ Res, vol 97: 512-23; Ishibashi et al. (1995), Arch Ophthalmol, vol 113: 227-31]. An agent that has an inhibitory effect on pericyte recruitment would likely disrupt vascular channel assembly and the maturation of the choroidal neovascular channels thereby perpetuating their sensitivity to anti-angiogenic agents.
Remodeling of the vascular network involves adjustments in BV density to meet nutritional needs [Gariano and Gardner (2005), Nature, 438: 960-6]. Periods of BV immaturity corresponds to a period in which new vessels are functioning but have not yet acquired a pericyte coating [Benjamin, Hemo and Keshet (1998), Development, 125: 1591-8 and Gerhardt and Betsholtz (2003), Cell Tissue Res, 2003. 314: 15-23]. This delay is essential in providing a window of plasticity for the fine-tuning of the developing vasculature according to the nutritional needs of the retina or choroid.
The bioactive lipid sphingosine-1-phosphate (S1P), VEGF, PDGF, angiopoietins (Ang) and other growth factors (GF) augment blood vessel growth and recruit smooth muscle cells (SMC) and pericytes to naive vessels which promote the remodeling of emerging vessels [Allende and Proia (2002), Biochim Biophys Acta, vol 582: 222-7; Gariano and Gardner (2005), Nature, vol 438: 960-6; Grosskreutz et al. (1999), Microvasc Res, vol 58: 128-36; Nishishita, and Lin (2004), J Cell Biochem, vol 91: 584-93 and Erber et al. (2004), FASEB J, vol 18: 338-40.32]. Pericytes, most likely generated by in situ differentiation of mesenchymal precursors at the time of EC sprouting or from the migration and dedifferentiation of arterial smooth muscle cells, intimately associate and ensheath ECs resulting in overall vascular maturity and survival [Benjamin, Hemo and Keshet (1998), Development, vol 125: 1591-8]. Recent studies have demonstrated that S1P, and the S1P1 receptor, are involved in cell-surface trafficking and activation of the cell-cell adhesion molecule N-cadherin [Paik et al. (2004), Genes Dev, vol 18: 2392-403]. N-cadherin is essential for interactions between EC, pericytes and mural cells that promote the development of a stable vascular bed [Gerhardt and Betsholtz (2003), Cell Tissue Res, vol 314: 15-23]. Global deletion of the S1P1 gene results in aberrant mural cell ensheathment of nascent BVs required for BV stabilization during embryonic development [Allende and Proia (2002), Biochim Biophys Acta, vol 1582: 222-7]. Local injection of siRNA to S1P1 suppresses vascular stabilization in tumor xenograft models [Chae et al. (2004), J Clin Invest, vol 114: 1082-9]. Transgenic mouse studies have demonstrated that VEGF and PDGF-B promote the maturation and stabilization of new BVs [Guo et al. (2003), Am J Pathol, 162: 1083-93 and Gariano and Gardner (2005), Nature, vol 438: 960-6.50]. VEGF up-regulates Ang-1 (mRNA and protein) [Asahara et al. (1998), Circ Res, vol 83: 233-40]. Ang-1 plays a major role in recruiting and sustaining peri-endothelial support by pericytes [Asahara et al. (1998), Circ Res, vol 83: 233-40]. Intraocular injection of VEGF accelerated pericyte coverage of the EC plexus [Benjamin, Hemo and Keshet (1998), Development, vol 125: 1591-8]. PDGF-B deficient mouse embryos lack micro-vascular pericytes, which leads to edema, micro-aneurisms and lethal hemorrhages [Lindahl et al. (1997), Science, vol 277: 242-5]. Murine pre-natal studies have demonstrated that additional signals are required for complete VEGF- and PDGF-stimulation of vascular bed maturation. Based upon the trans-activation of S1P noted above, this factor could be S1P [Erber et al. (2004), FASEB J, vol 18: 338-40]. Vessel stabilization and maturation is associated with a loss of plasticity and the absence of regression to VEGF and other GF withdrawal and resistance to anti-angiogenic therapies [Erber et al. (2004), FASEB J, vol 18: 338-40 and Hughes. and Chan-Ling (2004), Invest Ophthalmol Vis Sci, vol 45: 2795-806]. Resistance of BVs to angiogenic inhibitors is conferred by pericytes that initially stabilize matured vessels and those that are recruited to immature vessels upon therapy [Erber et al. (2004), FASEB J, vol 18: 338-40]. After ensheathment of the immature ECs, the pericytes express compensatory survival factors (Ang-1 and PDGF-B) that protect ECs from pro-apoptotic agents.
3. Edema and Vascular Permeability
CNV membranes are composed of fenestrated vascular ECs that tend to leak their intravascular contents into the surrounding space resulting in subretinal hemorrhage, exudates and fluid accumulation [Gerhardt and Betsholtz (2003), Cell Tissue Res, vol 14: 15-23]. For many years the CNV tissue itself, and more recently intra-retinal neovascularization, have been implicated as being responsible for the decrease in visual acuity associated with AMD. It is now thought however, that macular edema caused by an increase in vascular permeability (VP) and subsequent breakdown of the blood retinal barrier (BRB), plays a major role in vision loss associated with AMD and other ocular diseases [Hughes and Chan-Ling (2004), Invest Ophthalmol Vis Sci, vol 45: 2795-806; Felinski and Antonetti (2005), Curr Eye Res, vol 30: 949-57; Joussen et al. (2003), FASEB J, vol 17: 76-8 and Strom et al. (2005), Invest Ophthalmol Vis Sci, vol 46: 3855-8].
4. Fibrosis, Fibrogenesis and Scar Formation
The formation of subretinal fibrosis leads to irreversible damage to the photoreceptors and permanent vision loss. As long as the neovascular complex remains intact, as appears to be the case in patients treated with anti-VEGF agents, the potential for subretinal fibrosis and future vision loss persists. In an update of the PRONTO study of RANIBIZUMAB, it was discovered that those patients who lost vision did so as a result of either subretinal fibrosis or a RPE tear [Presentation. at Angiogenesis 2006 Meeting. 2006. Bascom Palmer Eye Institute Miami, Fla.]. An agent that could diminish the degree of fibroblast infiltration and collagen deposition would likely be of value.
Fibroblasts, particularly myofibroblasts, are key cellular elements in scar formation in response to cellular injury and inflammation [Tomasek et al. (2002), Nat Rev Mol Cell Biol, vol 3: 349-63 and Virag and Murry (2003), Am J Pathol, vol 163: 2433-40]. Collagen gene expression by myofibroblasts is a hallmark of remodeling and necessary for scar formation [Sun and Weber (2000), Cardiovasc Res, vol 46: 250-6 and Sun and Weber (1996), J Mol Cell Cardiol, vol 28: 851-8]. S1P promotes wound healing by activating fibroblast migration and proliferation while increasing collagen production [Sun et al. (1994), J Biol Chem, vol 269: 16512-7]. S1P produced locally by damaged cells could be responsible for the maladaptive wound healing associated with remodeling and scar formation. Thus it is believed that S1P inhibitors are useful in diseases or conditions characterized, at least in part, by aberrant fibrogenesis or fibrosis. Herein, “fibrogenesis” is defined as excessive activity or number of fibroblasts, and “fibrosis” is defined as excessive activity or number of fibroblasts that leads to excessive or inappropriate collagen production and scarring, destruction of the physiological tissue structure and/or inappropriate contraction of the matrix leading to such pathologies as retinal detachment or other processes leading to impairment of organ function.
The role of bioactive lipids, particularly S1P, in disease, including ocular disease, and anti-S1P antibodies, are described in detail in commonly owned U.S. Pat. No. 7,829,674, U.S. patent application Ser. No. 12/258,353, now issued as U.S. Pat. No. 7,956,173; commonly owned and co-pending U.S. patent application Ser. No. 12/258,383, now issued as U.S. Pat. No. 8,026,342; and commonly owned and co-pending U.S. patent application Ser. No. 11/925,173, now issued as U.S. Pat. No. 8,614,103. Anti-S1P antibody formulations are described in commonly owned and co-pending U.S. patent application Ser. No. 12/418,597. This application incorporates by reference for all purposes all of the aforementioned applications, each in its entirety.